The OPs clarification:
Assume there is a person that might want to hurt their educator for failing them by spreading lies or accusing them of something they didn't do (harassment during 1-1 meetings). How can that educator protect themselves (best practices, measures, etc.)?
changes the question somewhat. It's not about the one student in X (whatever X is) who is willing to risk mutual destruction to satisfy a grievance. In this case, I agree with StrongBad regarding general precautions. I would also be selective in which students to accept. There is nothing bad about it if done on an individual basis (instead of based on the sex of the person). After all, you need to work with the student and if the interaction does not work out, it's unlikely you'll both get something good out of it.
But your clarification sounds like there is a student out to get you. In that case, it might be helpful to talk with trusted colleagues who also know the student (about your difficulties with the student). It might even be time for legal support — someone who knows academia and knows how to deal with these cases. Also, "always be recording" might be helpful here (again: talk to a lawyer first).
In general I have found that conflicts with students (e.g. about grades) can be mediated if done correctly (needs a neutral and skilled mediator). However, this might not work for all students.
One issue I haven't found in the answers so far is a worst-case scenario plan for the unlikely but possible case of a false accusation happening. I find that with rare but devastating events, having a plan on how to deal with such a situation might help. You are unlikely to think clearly if that event occurs.
A website I have seen long ago (page no longer exists) listed a few tips in case of a wrongful accusation (albeit directed at students). Among others:
- not to talk with others about it (save close family or attorney; never ever talk about it on social media; you never know how it might be used against you),
- keeping your cool (influences perception)
- seeking independent counsel (the university might decide to protect its reputation)
- not use the university eMail/phone system (again: the university might not be neutral)
- be wary of pretext calls (friend calling you and trying to get you to admit guilt; just decline to answer any questions and hang up)
- be wary of physical danger (person who accuses you might instigate violence)
- never talk to the police if accused (let the attorney deal with it)
- getting to know the procedures on how the university deals with it (esp. to know your rights)
- recording anything that you are legally allowed to record (state laws! consult attorney)
- document-document-document — and keep everything organized
- adhere religiously to no-contact orders (even if the students wants you to call back or wants to meet)
- and the like.
Hopefully you never need it, but a worst-case plan might be helpful.
Talking about helpful, a comment about the question and some of the reactions here:
I think a false accusation is one of the worst things that can happen to a person. It can destroy a person's life, can socially isolate them, can drive them to suicide, and can undermine the basic trust in the legal system.
And yep, sexual misconduct/harassment/assault happens. A few people — male and female — are criminal assholes, no question about it, esp. in positions of power. But there also are a few people — male and female — who will use any method to get at someone. There is a phase in conflicts where even devastating personal losses are accepted just to get at the other person. It's not rational but deeply human. And in some cases, this can involve wrongful accusations.
Which sucks, given that most people in academia just want to do a good job — do good research and teach good courses — and these things make life unnecessarily difficult.
With this in mind, I wonder how some answers would read if you gender swap it (useful test to see biases). If the question had been about a female professor being afraid of possible physical violence from male students. After all, a wrongful accusation is essentially assaulting a person via a proxy, and over a longer time period. Here the proxy is the legal system, and sometimes also the court of public opinion (which sometimes comes with actual violence, not to mention violence in prisons).
In this swapped case, essentially saying: it's rare, bad things do not happen to good people, don't invite it, just be professional, and what's really important are cases of Y ... just does not cut it. It would probably be called "victim blaming" and "derailment". Yes, being professional is good advice, but it doesn't work if the student is not. Humans aren't always professional, or even rational.
So, with the question asked here I think it's best to ... well, assume the best: the OP just wants to do a good job and cases of false accusations just scare the shit out of many people. No matter how rare they are. And as useful as statistics are (which would have to be about false accusations), a person has only one life and the consequences are devastating. Even if the probability is low, if the consequences are serious enough it pays to prepare for such an event. That's why we have insurances.
So, kudos to the OP for asking the question and dealing with the reactions.